Material for plastic working and production method thereof

Abstract

A material for plastic working is produced by the steps of using a mold having a mold cavity ( 16 ) partially defined by an end surface of a stopper ( 13 ) for closing a molten metal inlet ( 101 ), teeming molten metal ( 10 ) into the mold cavity through the inlet and cooling the molten metal to thereby attain unidirectional solidification of the molten metal. Regulation of the cooling rate enables the mean grain size to be graded in the direction from the cooled face (B surface) to the opposing face (T surface) and the added components to increase in the same direction. It is possible to obtain a material for plastic working that has a selected portion exhibiting an excellent function.

1. A method for producing a material for plastic working in a mold having a mold cavity partially defined by an end surface of a stopper for closing a molten metal inlet, comprising the steps of teeming molten metal into mold cavity through the molten metal inlet and initiating cooling the molten metal from a time before closing the molten metal inlet to terminate the teeming to thereby attain unidirectional solidification of the molten metal, wherein a cooling rate of the molten metal is monotonously reduced in a direction from a cooled face of the mold to an opposing face of the mold, except for a columnar portion which is coaxial with and present beneath the molten metal inlet and has a diameter 1.5 times to twice that of the molten metal inlet. 
   
   
     2. The method for producing a material for plastic working as described in  claim 1 , wherein the columnar portion has a diameter 1.5 times that of the molten metal inlet. 
   
   
     3. The method for producing a material for plastic working as described in  claim 1 , wherein the columnar portion has a diameter twice that of the molten metal inlet. 
   
   
     4. The method for producing a material for plastic working as described in any one of  claims 1  to  3 , wherein the molten metal is aluminum alloy. 
   
   
     5. The method for producing a material for plastic working as described in any one of  claims 1  to  3 , wherein the molten metal is aluminum-silicon-based alloy.